They certainly thought they were being experimental, at least with in the context of Rock-N-Roll. Much like those in free jazz thinks it's experimental, but they still confine it to umbrella of jazz.

And really, in terms of the last 500 years, you could argue...

Snip!

In the end, it's all relative.

One definition of 'experimental' is the precedent. Is there a precedent for what you're hearing? If so, how ingrained is that precedent?

Let's take Beethoven as an example. I will argue that Beethoven - in his time - was largely experimental. He follows a level of tradition, but Beethoven's style of composition is actually radically different to anything before it. The differences are subtle to modern tastes, but they are profound and kickstarted the Romantic movement.

One thing that is drilled into you at an academic compositional level is precedent awareness. Can you talk about previous composers that have influenced you? Or concepts that have inspired you - and in doing so, can you differentiate yourself sufficiently and distinctly? Then there is the question of the naive. Are you naive? Can you not find a precedent? Can your music be approached naively?

All music at some point is experimental to a degree - but there are levels of importance within that. If we take a band like The Beatles whose later catalogue is experimental for the time, you can then look at that and trace roots of what they were doing to more avant-garde composers like Karlheinz Stockhausen (whether they were aware of it or not) and you finally arrive at somebody who was 'ahead of their time', i.e. with a less traceable precedent. Then you're usually in the grounds of the experimental proper.